Shares of Eli Lilly and Company (LLY 0.68%) were sinking 8.7% as of 10:42 a.m. EDT on Monday. The big drop came after the drugmaker presented data on Saturday from a phase 2 study of donanemab in treating Alzheimer's disease. Investors were disappointed by Lilly's results.
There was good news from Lilly's study. The company reported that donanemab met the primary endpoint of slowing decline on the integrated Alzheimer's Disease Rating Scale (iADRS) compared to placebo. The iADRS is a composite scale that measures cognition and daily function with Alzheimer's disease patients. Lilly said patients receiving donanemab had a 32% reduction in iADRS score compared to patients on placebo.
So why weren't investors impressed? Donanemab didn't meet a secondary endpoint of decline in another more widely used measurement for Alzheimer's disease patients: the Clinical Dementia Rating Scale–Sum of Boxes (CDR-SB).
Some probably couldn't help but recall that Lilly's solanezumab also performed well with the iADRS measure but didn't do so with the CDR-SB measure. Solanezumab went on to flop in late-stage testing.
Still, Lilly thinks donanemab could be a success. Daniel Skovronsky, chief scientific officer and president of Lilly Research Laboratories, said: "This is the first late-stage study in Alzheimer's disease to meet its primary endpoint at the primary analysis. Donanemab has the potential to become a very important treatment for Alzheimer's disease."
Lilly plans to complete enrollment in a second pivotal study of donanemab in the second half of 2021. The big pharmaceutical stock will probably need other catalysts to rebound from today's sell-off, though: The first results from this second study aren't expected until the first half of 2023.